Reformer for firing reverberatory furnace and method of operating said reformer

ABSTRACT

A reformer for firing a reverberatory furnace comprising a reaction chamber with a device for incomplete combustion of the gaseous and liquid hydrocarbon fuel accompanied by the formation of soot which is supplied into the working space of the furnace for ensuring a high luminosity of the flame.

United States Patent [191 Tesner et al.

[ 51 Jan. 22, 1974 REFORMER FOR FIRING REVERBERATORY' FURNACE AND METHODOF OPERATING SAID REFORMER [76] Inventors: Pavel Alexandrovich Tesner,ulitsa Chaplygina, 2, kv. 3; Konstantin Ivanovich Makarov,Khlebozavodskoi proezd, 5, korpus 2, kv. 370; Alexandr Kornilovichlvanov, ulitsa Raskovoi, 33, kv. 4 9;

Mark Anisimovich Robin, 2, kvertsl,

11, kv. 19; Igor Sergeevich Slavkin, ulitsa, Mira, 9, kv. 10; AlexandrPetrovich Pischulin, Proletarsky prospekt, korpus-1, kv. 30, all ofMoscow; Leonid Mikhailovich Pokrass, ulitsa Pionerskaya, 98, Donetsk;Alexandr Markovich Pochtman, ulitsa Prardy, 5, kv. 41v, Kharkov; FelixIsaakovich Sheinfain, ulitsa Postysheva, 120, kv. 18, Donetsk; EvgenyMikhailovich Kondratiev, prospekt Metallurgov, 107, Donetsk; Grigorylsaevich Moiseevich, ulitsa Postysheva', 122, kv. 54, Donetsk; IgorIvanovich Osmaga, bulvar Shevchenko, l7, kv. 53, Donetsk; GeorgyGavrilovich Zhitnik, bulvar Pushkina, 25, kv. 21, Donetsk, all ofU.S.S.R.

22 Filed: Nov. 7, 1912 21 App1.No.:304,307

Related US. Application Data [62] Division of Ser. No. 103,127, Dec. 31,1970,

abandoned.

[3 Foreign Application Priority Data .lan.4. 1970 UIS.S.R 1391905 [52]US. Cl. 266/24, 431/351 [51] Int. Cl. C21c 5/04 [58] Field of Search266/24, 33, l R; 431/351;

[56] References Cited UNITED STATES PATENTS 3,554,507 l/l97l Andonley etal. 431/351 Primary Examiner-Gerald A. Dost Attorney, Agent, orFirm-John C. Holman et a1.

[57] ABSTRACT A reformer for firing a reverberatory furnace comprising areaction chamber with a device for incomplete combustion of the gaseousand liquid hydrocarbon fuel accompanied by the formation of soot whichis supplied into the working space of the furnace for ensuring a highluminosity of the flame.

4 Claims, 1 Drawing Figure PATENTED JAN 2 21974 This is a divisional, ofapplication Ser. No. 103,127, filed Dec. 31, 1970 and now abandoned.

The present invention relates to the devices for firing reverberatoryfurnaces and more particularly it relates to the reformers for firingopen-hearth furnaces and to the method of their operation involvingpreliminary preparation of the fuel in order to ensure a high luminosityof the flame in the furnace.

The present invention can be used most successfully in reverberatoryfurnaces and fire-chambers whose efficient operation requires anintensively radiating and highly luminous flame.

Known in the art are devices for firing reverberatory furnaces withgaseous fuel, for example, natural gas, wherein the gas is preliminarilyreformed, i.e., incompletely burned which is accompanied by theformation of soot. Such a device disclosed in US. Pat. No. 3,345,054,and called reformer, has a fire-proof reaction chamber with acylindrical internal surface in which natural gas is reformed under theconditions conductive to a maximum .transformation of carbon containedin gas into soot. The hot soot-gas mixture obtained in the reformer ismixed with the non-reformed gas thus producing a fuel mixture. On beingintroduced into the furnace, this mixture, containing a required amountof soot, gives a cone of flame which is characterized by high luminosityand, in consequence, has a high degree of heat transfer by radiation tothe product being heated. This flame possesses the requisite rigidityowing to a high velocity of the fuel stream delivered into the furnace.

For a maximum efficiency of the reforming process, the gaseous fuel isburned incompletely in the reformer in a rotary turbulent diffusionflame. For this purpose the gaseous fuel is fed into the reactionchamber in the form of an axial stream through a correspondingly setbranch pipe of the burner device whereas the air is delivered through abranch pipe set tangentially to the cylindrical internal surface of thereaction chamber and installed in the front part of the reformer, on itsside wall. This produces a rotary diffusion flame in the reformerreaction chamber, this flame allowing more than 20% of the carboncontained in the gaseous fuel to be tr ansformed into soot. This isconsiderably more than can be obtained with other arrangements forincomplete combustion. The air consumption in this case is 0.35-0.45 ofthe stoichiometric consumption.

However, in such an arrangement said reformer cannot reform liquidhydrocarbons such as the fuel oil used habitually as a stand-by fuel or,in absence of natural gas, as the main fuel.

The fuel oil can also be used as an addition to the gaseous fuel forimparting the required luminosity to the flame, and is fed directly intothe working space of the furnace.

Under these conditions the fuel oil is delivered through spray nozzlesor injectors. In contrast to the gaseous fuel this leads to thenecessity of increasing the coefficient of surplus air and tounproductive utiliyation of a part of the furnace working space toprepare the fuel oil for burning. Besides, the soot yield in this caseis not higher than 1'0 percent of the carbon con tained in the fuel oil.This results in a higher consumptionof fuel per ton of the product.

An object of the present invention resides in eliminating the aforesaiddisadvantages.

The main object of the invention consists in providing a reformer withsuch a reaction chamber which would make it possible to use efficientlyboth the gaseous and liquid fuel and to produce a highly luminous flame.

According to the invention, this object is accomplished by providing thereformer chamber with a device for incomplete combustion of liquidhydrocarbon fuel, said device being installed near the device forincomplete combustion of the gaseous fuel and provided with a spraynozzle for supplying liquid fuel into the chamber. Such a universalburner device allows reforming both types of fuel and producing soot inthe amount sufficient for the high luminosity of the flame.

As compared with the known methods of compound firing of furnaces withgas and fuel oil, preliminary reforming of fuel oil makes it possible totransform into soot up to 30 percent of the carbon contained in fuel oiland to produce a highly luminous flame which requires a smaller amountof surplus air owing to preliminary preparation of the fuel forcombustion, thus reducing the consumption of fuel.

It is practicable that the liquid fuel should be supplied through an airatomizer spray nozzle which would be mounted coaxially inside the branchpipe supplying gaseous fuel in the burner device for firing gaseous fueland,'simultaneously, coaxially with relation to the reaction chamber. Asit has already been stated above, the air required for incompletecombustion is delivered tangentially to the cylindrical internal surfaceof the reaction chamber through a specially set branch pipe. Thisensures the optimum conditions for the maximum transformation of thecarbon contained in the fuel into soot, avoiding at the same time thesettling of carbon on the walls of the reaction chamber which interfereswith its normal functioning. Besides, this arrangement of the burnerdevice for liquid fuel ensures its easy installation, removal andreplacement, when necessary.

It is practicable that the branch pipe supplying gaseous fuel in thedevice for burning this fuel should have a diameter equalling to 0.1 0.4of the diameter of the reformer reaction chamber. This ensures arational relation between the velocities of the streams of air andgaseous fuel and a maximum soot yield. Besides, this makes it possibleto install the liquid fuel spray nozzle coaxially as it has beendescribed above, without interfering with the conditions required forindependent operation of the reformer on gaseous fuel.

In the preferable embodiment of the reformer reaction chamber, accordingto the invention, it is practicable that the reformer should incorporatesome known devices for independent control of the flow rate of air,gaseous fuel, liquid fuel and of the agent which atomizes liquid fuel.This agent may be gas, e.g., natural gas, or air supplied under therequired pressure. The independent supply of the above-mentionedsubstances allows the operator at the control desk to shift the reformerto operation on gaseous or liquid fuel or on their mixture with therequired consumption ratio of these fuels.

According to the invention, if the furnace is tired with liquid fuel,the latter is gasified before burning in the reaction chamber byincomplete combustion accompanied by the formation of soot.

lf gaseous fuel is not available, air is used for atomizing liquid fuel;besides, air can be used for complete combustion of a part of the liquidfuel outside the reaction chamber in the tunnel burners, from which theproducts of complete combustion are delivered tangentially to theinternal surface of the reaction chamber. For better aerodynamics of thestreams in the reaction chamber it is practicable to install an evennumber of tunnel burners, for example two burners opposed diametricallyto each other.

A substantial advantage of the present invention lies in reaching a 10percent economy of fuel as compared with the known methods of compoundfiring of furnaces with natural gas and fuel oil.

Described below is a preferable embodiment of the reformer according tothe invention with reference to the accompanying drawing (which is aschematic longitudinal section through a part of an open-hearth furnace,including its firing throat, and one of the reform ers communicatingwith said throat and furnace.

Installed in the firing throat I of the furnace 2 is a fire-proof nozzle3 of a known design, communicating through a refractory channel 4 withthe reaction chamber 5 of the reformer 6. The nozzle 3 is inclined tothe horizontal to suit the required conditions of product heating in thefurnace. The area through the channel in the nozzle 3 is selected so asto ensure the required velocity of the fuel mixture flow and to producea rigid flame. The nozzle 3 is fitted with a branch pipe 7 forintroducing the non-reformed part of gaseous fuel into the reformedproducts flowing through the nozzle.

The reaction chamber 5 of the reformer 6 accommodates devices forincomplete combustion of gaseous and liquid fuel. The burner device forgaseous fuel, e.g., natural gas, consists of a gas supply branch pipe 8and an air supply branch pipe 9. The branch pipe 8 is installedcoaxially with the reaction chamber 5 while the branch pipe 9 is settangentially to the internal cylindrical surface of the chamber 5. Theburner device for liquid fuel, e.g., fuel oil, comprises an air atomizerspray nozzle 10 ofa known design provided with a pipe 11 for thedelivery of the atomizing agent, as well as the above-mentioned branchpipe 9, a by-pass line 12 with a shutoff means 13 and a tunnel burner 14of a known design, adapted for complete combustion of fuel. The fuel maybe fuel oil, natural gas, coke gas or some other cheap fuel.

The spray nozzle 10 and the pipe 11 are set coaxially inside the branchpipe 8.

Part of the non-reformed gaseous fuel is supplied to the branch pipe 7through the pipeline 15. The air is supplied to the branch pipe 9through the pipeline 16 and the by-pass line 12. During operation of thetunnel burners 14 they are fed with fuel through the pipeline 17 whereasair is delivered through the pipeline 16. Part of the gaseous fuel beingreformed is delivered to the branch pipe 8 through the pipeline 18. Thereformed liquid fuel is delivered to the spray nozzle 10 through thepipeline 19. 1f the fuel is atomized by natural gas, the latter issupplied to the branch pipe 11 through the pipeline 20; if the fuel isatomized by air, the latter is supplied through the pipeline 21.

The pipelines 12, 15, 16, 17, l8, 19, 20 and 21 are fitted with shut-offmeans (gate valves), 13, 22, 23, 24, 25, 28, 26 and 27, respectively.

These means are provided with remote control included into the atuomaticsystem (not shown) of controlling the furnace firing and shifting thisfiring from one side of the furnace to the other.

If the open-hearth furnace is fired with gaseous fuel, e.g. natural gas,the shut-off means 23, 24, 26, 27 and 28 must be closed while theshut-off means 22, 13 and 25 must be open for admitting the requiredquantities of gas and air. It is recommended to reform and supplythrough the pipeline 18 about 40% of the entire amount of natural gasused for firing the furnace and to use about 4 m of air per l m ofnatural gas for incomplete combustion in the reaction chamber. At thisair-gas consumption ratio, when gas is supplied in an axial streamthrough the branch pipe 8 while air is supplied in a tangential streamthrough the branch pipe 9 the soot yield reaches a maximum. It ispracticable that the diameter of the branch pipe 8 should be 0.1-0.4 ofthe inside diameter of the chamber 5.

The hot soot-gas mixture produced in the chamber 5 flows through thechannel 4 into the nozzle 3 where it is mixed with the non-reformed partof cold gas supplied through the branch pipe 7. As the non-reformed gasis thus heated, the fuel mixture delivered into the furnace 2 form thenozzle 3 is better prepared for complete combustion; as a result, saidcombustion is accelerated and proceeds at higher temperatures. All thisincreases the radiation heat transfer of the flame.

When the furnace is fired simultaneously with gaseous and liquid fuelsthere may be different combinations of the flow rates of these fuels. Inone of the methods it is recommended to reform such a quantity of fueloil which corresponds to 20 percent of the total heat spent for firingthe furnace. In this case it is necessary to open correspondingly theshutoff means 13, 22, 27 and 28 to supply air for reforming the fuel oilthrough the by-pass line 12; the natural gas is fed through pipeline 15and branch pipe 7 into the reformed products flowing through the nozzle3; the natural gas is also supplied through the pipeline 21 foratomizing the fuel oil delivered through the pipeline 19.

It is also possible to use other combinations of the consumption ratioof the gaseous and liquid fuels delivered into the reaction chamber 5for the preparation of the hot sootgas mixture and into the nozzle 3 formixing cold gas with said mixture.

Though natural gas can be delivered for reforming into the reactionchamber 5 simultaneously with fuel oil, it is preferable to employ sucha layout where the fuel oil used for furnace firing is preliminarilyreformed and gasified so that the furnace is supplied through the nozzle3 with the products of reforming mixed with natural gas. Thus, thefurnace receives a spray of a fuel mixture consisting wholly of heatedgases containing soot. Subsequent flame firing of this gaseous fuelmixture proceeds with low surplus air coefficients characteristic onlyof the gaseous fuel and, correspondingly, at high temperatures. Thisensures a high luminosity of the flame and a high heat transfer byradiation.

When natural gas is not available and the furnace is fired with fueloil, it is necessary to close the shut-off means 22, 25, 27 and open theshut-off means 26 and 28 for delivering, respectively, air as anatomizing agent, and liquid fuel for reforming. The process of reformingcan in this case proceed owing to the-heat produced by the combustion ofthe part of fuel oil delivered into the chamber 5 through the spraynozzle 10.

The air is then delivered for reforming through the bypass line 12 andthe shut-off means 13.

The reforming process can also proceed owing to the heat produced by thecombustion of a part of fuel oil in the tunnel burners 14. It ispreferable to have an even number of tunnel burners l4 and arrange themdiametrically opposite to each other for better aerodynamics of thestreams in the chamber 5. In this case said burners are supplied withthe corresponding amounts of fuel oil and with the quantity of airsufficient for complete combustion of fuel oil. For this purpose theshut-off means 23 and 24 are opened through a required angle and theshut-off menas 13 are closed. The total recommended ratio of theconsumption of air and fuel oil delivered into the reaction chamber is 3m /kg. This amount includes the air spent for the atomization of fueloil. These conditions ensure the reforming time necessary for obtainingthe sufficient yield of soot as well as the preliminary gasification ofliquid fuel before burning it in the furnace. As a result, the fuelmixture delivered for flame burning contains combustible hot gases and asufficient proportion of soot. Owing to this the flame combustionproceeds with low coefficients of surplus air which are characteristiconly of gaseous fuel, and at high temperatures. This also ensures amaximum radiation of the soot contained in the flame.

While using liquid hydrocarbons as fuel, the invention makes it possibleto subject them to preliminary gasification and transform themsimultaneously into soot in the quantities required for high luminosityof the flame. The high temperatures produced by the burning of'suchprepared fuel increase the radiation of the soot in the flame and of theflame as a whole which intensifies the heat transfer and gives at leasta percent saving in fuel.

What we claim is:

1. A reformer for firing a reverberatory furnace comprising: a reactionchamber with a cylindrical internal surface communicating with theworking space of said furnace and intended for incomplete combustion init of the hydrocarbon fuel, said combustion being accompanied by theformation of soot to be delivered into the furnace; a device forincomplete combustion of gaseous hydrocarbon fuel located in saidreaction chamber; said device provided with a branch pipe supplyinggaseous fuel into said chamber and installed coaxially with the latter,and a branch pipe supplying air into the same chamber, locatedtangentially to the internal surface of said chamber; and a device forincomplete combustion of liquid hydrocarbon fuel, installed in saidchamber near said device for incomplete combustion of gaseous fuel andprovided with a spray nozzle for the supply of liquid fuel into saidreaction chamber.

2. A reformer according to claim 1 wherein there is an air atomizerspray nozzle for the supply of liquid fuel, located coaxially insidesaid branch pipe for the supply of gaseous fuel.

3. A reformer according to claim 1 wherein the diameter of said branchpipe for the supply of gaseous fuel into said reaction chamber is0.1-0.4 of the inside diameter of this chamber.

4. A reformer according to claim 1 wherein said devices for incompletecombustion of gaseous and liquid fuels are provided with known means ofindependent control of the flow rate of the air, gaseous and liquidfuels, and of the agent used for atomizing the liquid fuel.

1. A reformer for firing a reverberatory furnace comprising: a reactionchamber with a cylindrical internal surface communicating with theworking space of said furnace and intended for incomplete combustion init of the hydrocarbon fuel, said combustion being accompanied by theformation of soot to be delivered into the furnace; a device forincomplete combustion of gaseous hydrocarbon fuel located in saidreaction chamber; said device provided with a branch pipe supplyinggaseous fuel into said chamber and installed coaxially with the latter,and a branch pipe supplying air into the same chamber, locatedtangentially to the internal surface of said chamber; and a device forincomplete combustion of liquid hydrocarbon fuel, installed in saidchamber near said device for incomplete combustion of gaseous fuel andprovided with a spray nozzle for the supply of liquid fuel into saidreaction chamber.
 2. A reformer according to claim 1 wherein there is anair atomizer spray nozzle for the supply of liquid fuel, locatedcoaxially inside said branch pipe for the supply of gaseous fuel.
 3. Areformer according to claim 1 wherein the diameter of said branch pipefor the supply of gaseous fuel into said reaction chamber is 0.1-0.4 ofthe inside diameter of this chamber.
 4. A reformer according to claim 1wherein said devices for incomplete combustion of gaseous and liquidfuels are provided with known means of independent control of the flowrate of the air, gaseous and liquid fuels, and of the agent used foratomizing the liquid fuel.